1. Field of the Invention
The present invention relates to a catalyst useful in hydrogenating oxo aldehydes. The present invention also relates to a process for preparing the catalyst. The present invention further relates to a process for hydrogenating oxo aldehydes.
2. Description of Related Art
Oxo alcohols are employed commercially as plasticizers for polyvinyl chloride plastics. Oxo alcohols are currently prepared by hydroformylating olefins with synthesis gas in the presence of cobalt catalyst to produce oxo aldehydes. The oxo aldehydes are then hydrogenated over a solid catalyst to produce the corresponding alcohols.
Currently, three classes of hydrogenation catalysts are commercially employed. They are the following: sulfided alumina-supported nickel-molybdenum-(sulfided NiMo/Al2O3); sulfided alumina-supported cobalt-molybdenum-(sulfided CoMo/Al2O3); and bulk copper chromate (Cu/Cr). The sulfided catalysts are suitable for feedstocks containing or not containing sulfur, whereas the Cu/Cr alloys are effective only with sulfur-free feedstocks. Reaction product alcohol yields range from about 92% to 96% for the sulfided catalysts and about 98% for the Cu/Cr (%=mole percent).
Reduced bulk nickel-molybdenum catalysts have been used in the hydrogenation of benzene. Teachings to such use are described in the Journal of Catalysis, 91, 356–360 (1985), Applied Catalysis, 10, 63–76 (1984). Bulk sulfided nickel-molybdenum and nickel-molybdenum-tungsten catalysts are described in U.S. Pat. Nos. 5,382,715, 5,399,793, and 6,278,030 B1.
It is desirable to have a catalyst system for the hydrogenation of oxo aldehydes that provides higher yields and higher selectivity for oxo alcohols than prior art catalyst systems. It is further desirable to have a catalyst system that converts a higher proportion of by-products (i.e., acids, formates, and trimers) commonly found in oxo aldehyde feedstocks to oxo alcohols.
It was found surprising that there is a catalyst system for hydrogenation of oxo aldehydes that provided high yields and high selectivity for oxo alcohols. It was also found surprising that there is a catalyst system that also converts a significant portion of by-products (i.e., acids, formates, and trimers) commonly found in oxo aldehyde feedstocks to oxo alcohols. It was further yet surprising that there is a catalyst system for hydrogenation of oxo aldehydes that could be incorporated into a hydroformylation process for producing oxo alcohols from olefinic feedstreams. It was still further yet surprising that a non-sulfided alloy catalyst could be used with a sulfur-containing feedstream.